Roofing boards can include particle boards, gypsum boards, or foam insulation boards. Some include facers. Others do not. Polyiso insulation boards include facers for manufacturing (foam laydown) and to provide many of the product's performance properties. The majority of facers fall into two categories: Glass Reinforced Felt (GRF) or Coated Glass Faced (CGF). GRF facers are also known as “paper” facers given their craft paper appearance. GRF facers generally range in color from light brown to darker brown and are made from fiberglass reinforced pulp paper. CGF facers, on the other hand, tend towards white to off-white in color and are made by coating a non-woven fiberglass scrim. Insulation facers, whether GRF or CGF, are the same color on both sides of the board.
Adhering single-ply membranes to roofing boards, such as insulation boards is common practice and is becoming a more preferred method of roof installation. Each adhesive has its own requirements in terms of “setup time”. In other words, the adhesive has to flash-off, get to string time, etc. before the membrane can be adhered to the insulation. The setup time can vary dramatically based on the ambient environmental conditions (e.g., air temperature, insulation/membrane temperature, humidity, sunlight/solar energy, etc.) on the rooftop.